E-Bike motor im building

I havent found a bike to mount this on or a controller to power it yet, but its almost complete and just needs an adjustment on the 3d printer to finish it up (the gears are not all the exact same distance from the center). It uses (6) 775 dc motors that are rated at 12 volts and 150 watts (=900 watts), but I believe will handle twice that with no problems (1800 watts). I had the motors turning with a cheap controller I ordered off ebay but I only had 3 out of 6 motors installed, as soon as I installed the other 3 motors and turned it up half way it got stuck on full power with no response from the speed adjustment knob. This probably wouldn't be a good thing if the motor was put on a bike and the controller failed, also the amount of torque it did have just from 3 motors kind of scared me with the ratio of gearing it will have, I cant wait to see all 6 make something go. Also the chain/sprocket I'm using is #25 roller chain (pocket bike chain) so the sprocket inst naturally going to fit any bicycle.. But if anyone knows where to find a regular size bike sprocket with a 15mm bore and set screw lemme know. all feedback is welcome, this idea came from people attaching drills to bikes and achieving some credible speeds, I am just trying to see how far the limit of cheap parts will go compared to $500 e-bike motors that claim the same wattage. $500 would even be cheap if you compare the 1800 watt over-volt the dc motors should handle, and the total cost in parts for this motor including a roll of 3d printer filament was under $200, the most expensive components being the motors for $12/piece, and the gears at around $60 for the whole set (had to find cheap gears that had the same distances from the center as the 3D sketch I made, custom gears would have been out of the question, and the ratio ended up being 2:2) and about $2 for each bearing (4 were used). All feedback is appreciated!!

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